Sideroblastic Anemia

Content of This Page

1- Introduction

2- Pathophysiology

3- Clinical Features (Recognize chronic clinical features)

4- Interpret labs and diagnostics

5-Management of acute complications

6- Preventive strategies

7-Indications for transfusion & transplant

8- Complications

9- Prognosis & mortality trends

Introduction

Sideroblastic anaemia is a group of disorders characterised by defective incorporation of iron into haem, leading to ineffective erythropoiesis, iron accumulation in erythroblast mitochondria, and the appearance of ring sideroblasts in bone marrow.

© image from Wikimedia Commons

Pathophysiology

  • The defect is in haem biosynthesis, particularly at the step catalyzed by ALA synthase (ALAS2).

  • Iron is transported into mitochondria but not incorporated into haem, resulting in:

    • Ineffective red cell production

    • Mitochondrial iron overload

 

  • Can be:

    • Congenital (e.g. X-linked ALAS2 mutation)

    • Acquired: due to myelodysplastic syndromes (MDS), alcohol, lead, copper deficiency, or drugs (e.g. isoniazid)

Clinical Features

  • Often chronic microcytic anaemia with fatigue and pallor

  • May present with:

    • Splenomegaly

    • Iron overload signs: bronze skin, diabetes, hepatomegaly

 

  • Congenital forms present earlier; acquired forms more often in older adults

Interpret labs and diagnostics

  • Blood tests:

    • ↓ Hb, ↓/N MCV (often dimorphic)

    • ↑ Serum iron, ↑ Ferritin, ↑ Transferrin saturation

  • Blood film:

    • Basophilic stippling, target cells

  • Bone marrow:

    • Prussian blue stain shows ring sideroblasts

  • Consider:

    • Genetic testing (for congenital)

    • Lead levels, copper, and B6 status

    • Cytogenetics if MDS is suspected

Management of acute complications

  • Acute haemolysis or symptomatic anaemia may need blood transfusion

  • Manage iron overload (esp. with frequent transfusions):

    • Iron chelation (e.g. deferasirox)

  • Infections or marrow suppression → treat promptly

Preventive strategies

  • Avoid triggers: alcohol, toxins, offending medications

  • Vitamin B6 (pyridoxine) supplementation in congenital forms

 

  • Monitor and prevent iron overload in transfused patients

Indications for transfusion & transplant

  • Transfusion:

    • When anaemia becomes symptomatic or Hb critically low

 

  • Bone marrow/stem cell transplant:

    • Considered in refractory congenital cases or progression to MDS/leukaemia

Complications

  • Secondary haemochromatosis (iron overload)

  • Cardiomyopathy, endocrinopathies (diabetes, hypothyroidism)

  • In MDS-associated forms: progression to acute myeloid leukaemia (AML)

Prognosis & mortality trends

  • Depends on cause:

    • Reversible acquired forms (e.g. drug-induced) → good outcome with removal of trigger

    • Congenital or MDS-related forms → chronic disease, risk of progression

  • Monitoring for iron overload and marrow failure is essential

Scroll to Top